G. terenasus differs from other members of the complex by its relatively small size (females larger than males) distinctive colouration and pattern on the body, thin fins and a rounded snout profile when viewed from the side.

[2] Mainly olive brown on the back and sides above the lateral line and over the head and snout, lighter on the lower part of the body and silvery on the belly.

[2] Occurs in Far East Gippsland in Victoria and the extreme southeast of New South Wales in the mid reaches of the Snowy, Cann and Genoa river systems.Little historical data is available, however, specimens were captured from Curry Flat at Nimmitabel in 1914, near Bombala in 1938 and from Church creek near Delegate in 1965-6.

[2] G. terenasus is generally found in streams ranging from creeks to larger rivers, 1–12 m (3.3–39.4 ft) wides and 10–60 cm (3.9–23.6 in) deep, with slow to medium speed clear water.

Gravid females have been found with 220-240 quite small unshed eggs, 1.2 mm (0.047 in) in diameter on average, indicating a low fecundity for the species.